1. Field of the Invention
The present invention relates to a rotatable cylinder, and more particularly to a cylinder with a rotatable rod for a working machine such as a lathe.
2. Description of Related Art
A working machine such as a lathe always has a rotatable cylinder co-axially attached to the axle of the machine and connected to the clamping device of the machine. The rotatable cylinder can rotate with the axle of the machine and can actuate the clamping device to hold or to release a working piece. A hydraulic or a pneumatic pressure source is connected to the cylinder to control the extension and the retraction of the piston rod of the cylinder. Two check valves are mounted in the cylinder to release the pressure when the pressure applied to the cylinder is higher than a desired level. In the conventional cylinder, the check valves are attached to the flange of the piston.
However, with the check valves being attached to the flange of the piston, the flange has to be particularly thick which results in the piston being excessively heavy. Accordingly, this weight is detrimental to the operation of the lathe because of the torsion and axle load involved. To overcome the shortcomings, the present invention tends to provide a rotatable cylinder to mitigate or obviate the aforementioned problems.
The main objective of the invention is to provide a rotatable cylinder for a machine and having a lower weight than a conventional one. The cylinder has a rotating member, a cap, a piston, a collar, two control valves and two check valves. The piston is moveably mounted between the rotating member and the cap. The piston has a flange dividing the inner space between the rotating member and the cap into two chambers. The collar is mounted around the rotating member and has first and second I/O channels defined in the collar. The control valves are attached to the rotating member to respectively communicate with the chambers and further respectively communicate with the I/O channels in the collar. The check valves are attached to the rotating member to respectively communicate with the chambers and further respectively communicate with the I/O channels in the collar. Accordingly, the flange of the piston is relatively thin and thus the cylinder is lightweight whereby the cylinder and axle of the machine can be efficiently operated. Other objects, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.